One proposed structure of a cooling system includes a circulation flow path arranged to circulate a coolant for cooling down an engine, a branch flow path branched off from the circulation flow path and arranged to flow the coolant into a motor and an inverter, and an electric pump configured to pressure-feed the coolant through the circulation flow path (see, for example, Patent Document 1). In this proposed structure of the cooling system, the electric pump is controlled to increase the flow rate of the coolant with an increase in temperature of the coolant flowed through the engine and with an increase in temperature of the coolant flowed through the motor, for the purpose of adequately cooling down the engine and the motor.
Patent Document 1: Japanese Patent Laid-Open No. 2002-227644